In 2008, a nine-year-old girl in Georgia received a vaccine that aggravated her pre-existing cellular disease. After receiving inoculations, the disease caused a brain disorder that led to severe damage and led to the child displaying autism-like symptoms.
In children, it is not always possible to detect underlying conditions. Any child could be carrying a disease similar to the one mentioned above without any doctor knowing. This makes vaccines exceptionally risky and unsafe.
The exception proves the rule. The case was such a high-profile one precisely because it was so rare. By and large, vaccines are exceptionally safe for approximately 99.5% of the population. In the rare cases where the child may have a pre-existing condition that could be aggravated by inoculations, doctors are able to provide medical exemptions for diseases. In the US, approximately 0.05% of children enrolled in schools are exempt from inoculations on medical grounds. Setting the Bar for Safety Impossibly High If parents ruled out inoculations and medical procedures that had the possibility of aggravating an undiagnosed illness, they would deny their child almost all medical treatment. Almost all treatments carry the risk of aggravating an undiagnosed illness in some form. We must devise a standard for "safety" that means that the risk of aggravating an underlying illness or disease is sufficiently small to justify the widespread use of the treatment. Vaccines would meet this standard for safety, even if it cannot be called 100% safe.
[P1] Vaccines can aggravate underlying existing conditions. [P2] Therefore, they are not safe.
[Rejecting P1] This only occurs in very exceptional cases. [Rejecting P2] Therefore, we can accept that vaccines, relatively speaking, are a safe form of medical treatment.